Background: GeriPACT is a ?Special Population PACT? designed to provide comprehensive primary care combined with specialty expertise for complex geriatric and high-risk Veterans. GeriPACT strives to optimize independence, quality of life, and quality of care for Veterans who are particularly vulnerable due to multiple interacting cognitive, functional, psychosocial, and medical challenges in the setting of advanced age. Preliminary findings from the evaluation of GeriPACT led by the Geriatrics and Extended Care Data Analysis Center (GEC DAC) has demonstrated that care for complex patients in GeriPACTs costs 40-60% less than caring for similar patients in traditional PACTs. Although this is an important and compelling finding, we lack essential information about how GeriPACT differs from traditional PACT care in terms of clinical processes and patient experience of care. This information is essential for understanding the overall net benefit of the model, and understanding how best to target this service to patients that stand to yield the greatest benefit from enrollment. Methods: The main objective of this study is to understand the impact of GeriPACT on patient experience and key quality of care measures that may be contributing to observed cost differences. This prospective matched comparative effectiveness study will address the following specific aims: (AIM 1) To examine quality of care clinical process measures among Veterans cared for in GeriPACT, compared to similar patients in traditional PACTs. We hypothesize that Veterans cared for in GeriPACT will have fewer potentially inappropriate medications (PIMs) at 6, 12, and 18 months; higher rates of completed advance directives at 18 months; and higher performance on frail elder quality measures at 12 months. (AIM 2) To examine patient experience of care among Veterans cared for in GeriPACT, compared to similar patients in traditional PACTs. We hypothesize that Veterans in GeriPACT will have more days alive and at home (defined as days not in the emergency department (ED) or hospital) at 18 months; greater perceived care integration at 6, 12, and 18 months; and higher self-reported health and well-being at 6, 12, and 18 months. Finally, clinicians and Geriatrics and Extended Care leaders have identified sub-populations expected to differentially benefit from GeriPACT care but these subpopulations have not been examined empirically. Thus, Aim 3 is to examine whether the relationship between GeriPACT exposure and outcomes differs based on cognitive status, functional disability, or multiple chronic conditions (MCC). We hypothesize that impaired cognitive status, functional disability, and MCC will moderate the effects of GeriPACT on quality of care measures (increased effects) and experience of care (increased effects). Using targeted recruiting strategies to increase homogeneity between GeriPACT and PACT patients, along with coarsened matching and minimum distance score methods to derive a balanced sample, we will examine between-person changes between GeriPACT and PACT patients, controlling for initial health status. By combining data from a patient-reported survey and VHA electronic health records, we will minimize sources of bias that commonly plague comparative effectiveness studies. Anticipated Impact: More than half of all Veterans receiving primary care in VHA are aged 65 or older and the proportion of older patients is growing rapidly; however more than 40% of VAMCs do not have GeriPACT. The results of this study will provide critically-needed information to guide decisions about optimal dissemination and scale of this model of care designed to serve a large and growing population of older and medically complex Veterans. The results will be of great relevance outside VHA as health systems and Accountable Care Organizations throughout the U.S. look for effective primary care models to improve quality and value for older Americans.